1. Field of the Invention
This invention relates to Group Transfer Polymerization catalyzed by selected silanes, preferably in the presence of a suitable mercury compound and/or Lewis acid.
2. Background
U.S. Pat. Nos. 4,414,372; 4,417,034; 4,508,880; 4,524,196; 4,581,428; 4,588,795; 4,598,161; 4,605,716, 4,622,372; 4,656,233; 4,659,782; 4,659,783; 4,681,918; 4,695,607; 4,711,942; and 4,732,955; and in commonly assigned U.S. patent applications Ser. Nos. 912,117 filed Sept. 29, 1986; 934,826 filed Nov. 25, 1986; 004,831 filed Jan. 13, 1987; 007,758 filed Jan. 27, 1987; 015,727 filed Feb. 27, 1987; and 048,958 filed May 19, 1987; referred to hereinafter as "the aforesaid patents and patent applications", disclose processes for polymerizing an acrylic or maleimide monomer to a "living" polymer in the presence of:
(i) an initiator which is a tetracoordinate organosilicon, organotin or organogermanium compound having at least one initiating site; and
(ii) a co-catalyst which is a source of fluoride, bifluoride, cyanide or azide ions or a suitable Lewis acid, Lewis base or selected oxyanion. Such polymerization processes have become known in the art as Group Transfer Polymerization (Webster et al., J. Am. Chem. Soc., 105: 5706 (1983)).
Preferred monomers for use in Group Transfer Polymerization are selected from acrylic and maleimide monomers of the formula CH.sub.2 .dbd.C(Y)X and ##STR1## and mixtures thereof, wherein:
X is --CN, CH.dbd.CHC(O)X' or --C(O)X'; PA1 Y is --H, --CH.sub.3, --CN or --CO.sub.2 R, provided, however, when X is --CH.dbd.CHC(O)X', Y is --H or --CH.sub.3 ; PA1 X' is --OSi(R.sup.1).sub.3, --R, --OR or --NR'R"; PA1 each R.sup.1, independently, is a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms or --H, provided that at least one R group is not --H; PA1 R is: PA1 each of R' and R" is independently selected from C.sub.1-4 alkyl. PA1 each Q', independently, is R.sup.1, OR.sup.1, SR.sup.1 or N(R.sup.1).sub.2 ; PA1 R.sup.1 is as defined above for the monomer; PA1 Z is an activating substituent selected from the group consisting of ##STR2## and mixtures thereof; R', R", R and R are as defined above for the monomer; PA1 Z.sup.1 is ##STR3## X.sup.2 is --OSi(R.sup.1).sub.3, --R.sup.6, --OR.sup.6 or NR'R"; R.sup.6 is PA1 each of R.sup.2 and R.sup.3 is independently selected from -H and hydrocarbyl, defined as for R.sup.6 above, subparagraphs (a) to (e); PA1 R', R" and R.sup.1 are as defined above for the monomer; PA1 Z' is as defined above for the monomer; PA1 m is 2, 3 or 4; PA1 n is 3, 4 or 5; PA1 R.sup.2 and R.sup.3 taken together are ##STR4## provided Z is ##STR5## X.sup.2 and either R.sup.2 or R.sup.3 taken together are ##STR6## provided Z is ##STR7## and M is Si, Sn, or Ge, provided, however, when Z is ##STR8## M is Sn or Ge. PA1 each R.sup.1, independently, is a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms or --H, provided that at least one R.sup.1 group is not --H; and PA1 Z.sup.2 is a weakly basic radical, for example, I, Br, Cl, CF.sub.3 SO.sub.3, CF.sub.3 CO.sub.2, ClO.sub.4 or SO.sub.4 ; and
(a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms; PA2 (b) a polymeric radical containing at least 20 carbon atoms; PA2 (c) a radical of (a) or (b) containing one or more ether oxygen atoms within aliphatic segments thereof; PA2 (d) a radical of (a), (b) or (c) containing one or more functional substituents that are unreactive under polymerizing conditions; or PA2 (e) a radical of (a), (b), (c) or (d) containing one or more reactive substituents of the formula --Z'(O)C--C(Y.sup.1).dbd.CH.sub.2 wherein Y.sup.1 is --H or --CH.sub.3 and Z' is O or NR' wherein R is as defined below; and PA2 (a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms; PA2 (b) a polymeric radical containing at least 20 carbon atoms; PA2 (c) a radical of (a) or (b) containing one or more ether oxygen atoms within aliphatic segments thereof; PA2 (d) a radical of (a), (b) or (c) containing one or more functional substituents that are unreactive under polymerizing conditions; or PA2 (e) a radical of (a), (b), (c) or (d) containing one or more initiating sites; and
Preferred initiators are selected from tetracoordinate organosilicon, organotin and organogermanium compounds of the formulas (Q').sub.3 MZ, (Q').sub.2 M(Z.sup.1).sub.2 and [Z.sup.1 (Q').sub.2 M].sub.2 O wherein:
Preferred co-catalysts are selected from a source of bifluoride ions HF.sub.2.sup.-, or a source of fluoride, cyanide or azide ions, or a source of oxyanions, said oxyanions being capable of forming a conjugate acid having a pKa (DMSO) of about 5 to about 24, preferably about 6 to about 21, more preferably 8 to 18, or a suitable Lewis acid, for example, zinc chloride, bromide or iodide, boron trifluoride, an alkylaluminum oxide or an alkylaluminum chloride, or a selected Lewis base.
Additional details regarding Group Transfer Polymerization can be obtained from the aforesaid patents and patent applications, the disclosures of which are hereby incorporated by reference.
Razuvaev et al., Vysokomol.Soedin.(B), 25(2):122-125 (1983) disclose polymerization of methyl methacrylate and/or styrene initiated by a mixture of silicon tetrachloride and alkyls of mercury, tin or lead, at 20.degree.-50.degree. C. Sakurai et al., Tetrahedron Lett., 21:2325-2328 (1980) disclose mercuric iodide catalyzed isomerization of (trimethylsilylmethyl)chloromethyl ketone to (1-chloromethyl ethenyl)oxytrimethylsilane.
Burlachenko et al., Zhur, Obshchei Khim., 43(8):1724-1732 (1973) disclose isomerization of cis-ketene silyl acetals into the trans-isomer catalyzed by triethylsilyl bromide and mercuric bromide. Litvinova et al., abstract of Dokl. Akad. Nauk. SSSR, 173(3):578-580 (1967); CA 67: 32720j, disclose the mercuric iodide-catalyzed rearrangement of triethylacetonylsilane to (isopropenyloxy)triethylsilane.
Baukov et al., abstract of Dokl. Akad. Nauk. SSSR, 157(1):119-121 (1964); CA 61: 8333f, disclose the mercuric iodide-catalyzed rearrangement of [(1-methoxy-1-ethenyl)oxy]triethylsilane to methyl 2-triethylsilylacetate.
Satchell et al., Qtr. Rev. Chem Soc., 25:171 (1971) disclose that mercuric halides are very weakly acidic Lewis acids.
Weber, "Silicon Reagents for Organic Synthesis", New York, 1983, Chapter 3, pp 21-39 describes preparation and reactions of trimethylsilyl iodide, bromide and trifluoromethanesulfonate (triflate). These reagents are used as catalysts for cleaving chemical bonds in organic compounds and as silylating agents. They are often used in conjunction with organic bases such as pyridine. A more extensive survey of reactions catalyzed by trimethylsilyl triflate and trimethylsilyl esters of "Nafion" perfluorsulfonic acid resin is provided by Noyori et al., Tetrahedron, 37 (23), 3899 (1981).
U.S. Pat. No. 3,478,007 discloses polymerization of unsaturated cyclic hydrocarbons using aluminum chloride and a trialkylsilicon halide as catalyst; AlCl.sub.3 and trimethylsilyl chloride are exemplified.
Toshima et al., Kogyo Kagaku Zasshi 72(4), 984 (1969) discloses polymerization of styrene catalyzed by trimethylsilyl chloride and mercuric chloride.
The above publications do not suggest the use of trialkylsilyl halides with or without added Lewis acids or mercuric compounds as catalysts for Group Transfer polymerization.
U.S. Pat. No. 4,732,955, supra, discloses Group Transfer Polymerization of one or more acrylate or acrylamide monomers in the presence of a mercury compound of the formula R.sup.7 HgI, wherein R.sup.7 is a C.sub.1-10 hydrocarbyl radical, or HgL.sub.2, wherein L is I or ClO.sub.4. Commonly assigned U.S. patent application Ser. No. 176,807 concurrently filed herewith discloses the use of these mercury compounds, and also Lewis acid/silane mixtures, as catalysts in the preparation of 1:1 adducts of silyl ketene acetals and .alpha.,.beta.-unsaturated compounds, the adducts being effective GTP initiators.
Commonly assigned U.S. patent application Ser. No. 015,727, supra, discloses Group Transfer Polymerization in the presence of a non-initiating silylated ester or ether, preferably trimethylsilyl 3-chlorobenzoate, said ester or ether serving as a "livingness" enhancing agent.
The present invention provides an improved Group Transfer Polymerization process wherein the catalyst is a selected non-polymerization-initiating silane or a mixture thereof with a suitable mercury compound and/or Lewis acid. Mercury compounds disclosed herein are also disclosed for another use in the commonly assigned application filed herewith under Docket No. CR-8417, supra.